From mid-May through late September, a hydrofoil leaves Vienna Wednesdays, Fridays, and Sundays at 9 am . Return journeys from Budapest to Vienna are on Tuesday, Thursday, and Saturday. After a 5½-hour journey downriver, with a stop in the Slovak capital, Bratislava, and views of Hungary's largest church, the cathedral in Esztergom, the boats head into Budapest via its main artery, the Danube. The upriver journey takes about an hour longer.
Mahart Passnave. Budapest, Budapest. 1/484–4000; www.mahartpassnave.hu.